<!DOCTYPE html>
<title>Reference for default scroll() timeline with vertical-rl</title>
<meta name="viewport" content="width=device-width,initial-scale=1,minimum-scale=1">
<style>
  html {
    min-block-size: 100%;
    padding-block-end: 100px;
    writing-mode: vertical-rl
  }

  #box {
    width: 100px;
    height: 100px;
    background-color: green;
    transform: translateX(-100px);
  }

  * {
    margin-block: 0px;
  }
</style>

<div id="box"></div>

<script>
  window.addEventListener('load', function() {
    // Move the scroller to halfway.
    const scroller = document.scrollingElement;
    const maxScroll = scroller.scrollWidth - scroller.clientWidth;
    scroller.scrollLeft = -0.5 * maxScroll;
  });
</script>
